It is found that there are various factors that may cause an unstable operation of a gasification apparatus, and one common condition is an unexpected feeding interruption of coal material such that an uneven distribution of coal at the outlet of the powder channel is occurred. As a result, the local oxygen-coal ratio increases sharply and therefore the gasification apparatus will be over heated locally, which consequently may lead to a concatenation of shut down of the system or even a damage to the gasification apparatus during operation. This will cause a severely negative impact on the safety, stability and cost-efficiency of the gasification apparatus.
In the known gasifying coal technology, Texaco Co. provides a single burner arranged in atop position and utilizing coal-water slurry as its fuel, which includes three channels for transporting combustion materials: a central channel for oxygen, a second channel for coal-water slurry and an outermost channel again for oxygen. When the coal-water slurry feeding in the second channel is suddenly interrupted, the flow of the coal slurry at the burner nozzles will decrease sharply and inevitably result in shut down of the system. Furthermore, the interruption of coal feeding results in increasing of oxygen-coal ratio instantly, in turn increasing of the temperature of the furnace and aggravating the oxidative corrosion therein, which will cause disadvantageous affects on the furnace wall and the burner.
Shell Co. provides a powdered coal gasifying burner which utilizes powdered coal as a fuel. The apparatus burning the powdered coal is configured as four separated burners which are arranged at the middle or lower part of the furnace cavity evenly along a circumference direction, and these four burners produce flames opposed to one another in the furnace cavity, and the synthesis gas as a resultant is discharged from the upper end of the gasifying furnace while the slag is discharged from the lower end. In this apparatus, each burner has an independent feeding conduit and a corresponding control system, such that upon interruption of feeding coal of one feeding conduit, the other burner symmetrically opposed thereto can be shut down and the rest two burners in opposed positions remain to work to ensure the uniformity of the temperature field in the furnace, which may prevent a damage to the elements due to a deviant combustion. However, the even arrangement of four burners in the furnace cavity requires a precise manufacturing and installation of the burners; and moreover, the above-mentioned arrangement cannot give a solution to the problem that the interruptions of coal feeding are occurred in two feeding conduit of burners located in asymmetric positions at the same time, resulting in the deviant combustion, the oxygen-coal ratio sharply increased and the temperature of the furnace increased, therefore the oxidative corrosion will be aggravated and the furnace wall and the burner may still be damaged.
The applicant of this application disclosed a swirl burner for combustible powder under CN invention patent publication No. CN1710333A, which comprises 2-5 powder tubes arranged in a powder channel of the burner and distributed evenly along a circumference direction of the powder channel. The object of the invention is to adjust the workload of burner by adjusting the supply amount of the powders via increasing or reducing the tubes, and to prolong the service life of burner by optimizing the cooling effects by means of a multi-compartment cooling mechanism. However, there also exist in said powder burner similar problems that, in the event that one or several powder tubes fail or the feeding thereof is interrupted, the non-uniform burning is occurred at the outlet of the powder channel, resulting in higher temperature of the furnace, which will in turn destroy the furnace wall and the burner.